1. Chapman profile approach for 3-d global TEC representation;Feltens,1998
2. Die Ionosphären-Arbeitsgruppe des Internationalen GPS Service (IGS);Feltens,2000
3. GPS data collected during August 1999 solar eclipse;Feltens;Crustal Dynamics Data Information System (CDDIS) bulletin,1999
4. High-Rate SolarMax IGS/GPS campaign “HIRAC/SolarMax”;Feltens;Crustal Dynamics Data Information System (CDDIS) bulletin,2001
5. Estimation of GPS receiver and satellite L1L2 signal delay biases using data from CACS;Gao,1994